Tuning seismic resolution by frequency shift

Abstract

Resolution, in exploration seismology, is traditionally associated with the spectrum of the wavefield its effective bandwidth and its effective central frequency. The larger the bandwidth, the higher the resolution. If the bandwidth is kept the same, the seismic time resolution can be tuned up by increasing the dominant frequency of the signal or by the heterodyning technique in the terminology of radio communication. Heterodyning has been long exploited by communication engineers to translate signal spectra and make trade-offs between bandwidth and signal-to-noise levels in transforming signals from amplitude- to phase-modulated form. In the mapping of subsurface structures, phase information is as important as the shape of the envelope of the seismic signals. In this paper, we argue that heterodyning, if applied properly, enables a trade-off between detection precision and the signal-to-noise structure of the seismic data field. This will be illustrated by using synthetic and real data examples.